Fuel injection system



J. F. ARMSTRONG FUEL INJECTION SYSTEM Oct. 27, 1964 I5 Sheets-Sheet 1Original Filed Jan. '7, 1957 INVENTQR. JAMES FRED ARMSTRONG AT TORNEY:

Oct. 27, 1964 J. F. ARMSTRONG FUEL INJECTION SYSTEM 3 Sheets-Sheet 2Original Filed Jan. '7, 1957 ATTORNEY Oc 2 1964 J. F. ARMSTRONG FUELINJECTION SYSTEM 5 Sheets-Sheet 3 Original Filed Jan. 7, 1957 INVENTOR.JAMES FRED ARMSTRONG ATTORNEY United States Patent 25,672 FUEL INJECTIONSYSTEM James F. Armstrong, Kirkwood, Mo., assignor to ACE Industries,Incorporated, New York, N.Y., a corporation of New Jersey Original No.3,029,800, dated Apr. 17, 1962, Ser. No.

632,798, Jan. 7, 1957. Application for reissue July 31,

1962, Ser. No. 214,796

16 Claims. (Cl. 123-419) Matter enclosed in heavy brackets [1 appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention is an engine charging device using the continuous flowsystem adapted for port injection, in which system the fuel ispressurized, measured under pressure in accordance with enginerequirements, and distributed under pressure to points adjacent theintake valves of the several cylinders or combustion chambers of theengine. Such a system is shown in my prior application, Serial No.516,358, filed June 20, 1955, now Patent No. 2,785,669 and entitledInjection Carburetion, of which this application is acontinuation-in-part.

The charge forming device shown in this prior application comprises aplurality of sensing means for engine fuel requirements, preferablyresponsive to the rate of air fiow to the engine through the airinduction system, and engine pressures and temperatures for indicatingthe fuel requirements of the engine. These sensing means, in turn,control fuel metering means in passages supplied with fuel under pumppressure which deliver the metered fuel to the engine.

This application is also a continuation-in-part of my prior applicationS.N. 622,917 filed November 19, 1956, now patent No. 2,876,758.

According to this invention, the basic system above referred to has beenmodified in a manner to obtain a more stable datum pressure for moreprecise control of fuel metering.

According to this invention, the operating device for stabilizing thedatum pressure controls a by-pass device for bleeding the datum linerapidly of fuel displaced by movement of the diaphragms opening theseveral nozzle valves to increase the flow of fuel to the combustionchambers of the engine.

According to this invention, the air flow measuring device in the engineinduction system, which in turn controls the fuel metering, has beenmodified to obtain a variable response depending upon the degree andrate of the throttle valve opening. In this manner, the fuel flow to theengine can be increased and decreased depending upon engine load.

According to this invention, the pressure control device in the datumcircuit, together with a means for modifying the rate of response of theair flow measuring device, comprise cooperating devices to improve thethrottle response of the fuel system.

According to this invention, a means has been provided to increase thefuel fiow for acceleration, which acts directly to effect operation ofthe fuel metering means by modifying the response of the air valve tothe rate of air flow, causing the air valve to over-travel and the fueldelivery to increase when the throttle is opened.

According to this invention, the different fuel requirements of theengine at part throttle and full throttle loads are satisfied by a novelmeans, changing the fuel flow metering means by acting directly toaffect air valve response to variation in the rate of air flow.

The accompanying drawings are illustrative of system modifications whichwill carry out the objects of this invention.

Re. 25,672 Reissuecl Oct. 27, 1964 "ice In the drawings:

FIG. 1 is a schematic representation showing the interconnection of theelements of the system.

FIG. 2 is a schematic representation of a modification of the abovedescribed system.

FIG. 3 is a schematic representation showing the interconnection ofsimilar elements forming a second modification.

FIG. 4 is a modified form of air horn.

In the detailed description of the invention which follows, the samereference characters Will be used where possible to indicate theelements in this system corresponding with those in my prior identifiedapplications.

ENGINE CHARGING FUEL SYSTEM In FIG. 1 the fuel supply line 19 from thefuel tank connects with the inlet of the pump P. The outlet of the pumpP connects by way of line 20 through a check valve with the pressureregulator 22. Within the pressure regulator is a diaphragm 22c actedupon by the pressure of the fuel passing the valve 22b controlled by thediaphragm. The spring 22d acts upon the rear face of the diaphragm 22cin a direction to open the valve 22b. The casing enclosing the spring22d is generally vented to atmospheric pressure. A filter 21 is enclosedwithin the pressure regulator 22 to trap foreign matter passing throughto the pressure regulator from the pump and the check valve.

Fuel chamber A is supplied from the pump P through the pressureregulator 22 by way of a line 20a. Within the fuel chamber A are aplurality of metering rods 33 operated within metering orifices 23 by acrosshead device 34. The position of the rods 33 is, in turn, controlledby a magnetic clutch 35 from a shaft 36 operated by an air valve in theair induction system of the engine hereinafter described.

Each metering orifice 23 is connected by a separate line 24 with a fuelnozzle 25. There are as many fuel nozzles as there are cylinders of theengine, but only one has been shown here.

Each nozzle 25 has a stem portion 25a which may be fixed within thecylinder head or induction manifold for the engine, so as to dischargefuel adjacent an intake valve 26 of an individual cylinder of the engine(not shown). Within the stem 25a is a valve element 29 controlling theoutlet port of the nozzle, and this valve element 29 is, in turn,controlled by a diaphragm 28.

The lines 24, one of which is shown, connect with chambers 30 formed bythe diaphragm 28 and the outer housing for the nozzle 27. A cap 57secures the diaphragm in place and forms a second chamber 57 on theopposite side of the diaphragm 28 to which the datum pressure controlline is connected.

THE DATUM PRESSURE SYSTEM The datum pressure system connects With eachof the chambers 57 of the nozzles 25, and the fuel pressure therein isestablished by the action of two pressure regulators controlling theinlet and the outlet therefrom, and, incidentally, the pressure dropacross a discharge restriction from the datum pressure system to theinlet of the pump P. Fuel pressure is supplied to the datum system fromthe chamber A by Way of a line 56 to pressure regulator C. Thisregulator comprises a casing 70 containing a diaphragm 71 dividing thecasing into a pair of chambers 72 and 73. A spring 74 acts in adirection on the diaphragm 71 tending to close the valve 75 which isoperated from the diaphragm. The valve 75 forms a variable restrictionfor charging the datum system. A small valve 76 is biased to a closedposition by a spring 77 and has a stem 78 arranged for contact by thevalve 75, so that when the valve 75 closes, the valve 76 is opened toallow fuel to escape through a by-pass line 79 to the pressure regulator60. Datum pressure line 58 is supplied with fuel under pressure fromline 56 when valve 75 is open, and has a connection 59 with chamber 73of the pressure regulator C. Line 58 extends to the 5 datum pressurechamber of each of the nozzles 25 by way of the series of branches 58a,58b, 58c and 58d. At the outlet of the datum pressure line 58 is ametering restriction 61 in the form of a centrifugal jet or orifice.

Downstream of the orifice 60 which has a chamber 164 therein formed by adiaphragm 165. A passage 163 connects chamber 164 with the meteringrestriction 61. Diaphragm 165 has a plunger 168 operating against alever 169 which, in turn, controls the degree of opening of valve 167.Spring 166 the pressure of fuel in the chamber 164 on the diaphragm 165.

The lower portion of the casing of pressure regulator 60 has a pivotedlever 172 forced upwardly by the com- 61 is the pressure regulator whichis pivoted on the fixed structure of the air horn B. Piston 105 isconnected with the free end of lever 101 by a link 104. The piston 105rides in a cylinder 106 and is operated therein by a spring 107 actingin one direction and by engine suction acting in the opposite direction.Line 108 connects between the bottom of the cylinder 106 and a suctionport 116 in the air horn B downstream of the throttle 50.

AIR FLOW SENSING MEANS Connected with the air valve 37 is a link 39which extends through the wall of air horn B and is attached to adiaphragm 40 which separates chambers 41 and 42 within a casing attachedto the air horn B. A spring 43 resists acting against the back of thediaphragm 40 urges the valve 37 in a closing direction. An opening forceon the valve is supplied from a servo-motor, which in turn is poweredbythe difference in pressures across the valve 37 as sensed by a vent tube44 and a Pitot tube 45 conpression spring 180, whi h applies a fo e bway f nected with the chambers 41 and 42, respectively, of the the pivot170 to the lever 169.

ENGINE PRIMING AND UNLOADING CONTROL A battery 194 is connected to theground at one termial, and has the other terminal connected by Way of:ad 196 to an ignition switch 197 for the ignition system f the engine.Connected in series with the ignition wtch 197 is a starter switch Scontrolling the flow of urrent through a lead 198 to starter motor 195and 1e circuit to energize terminals 184 and 191 of the witch 28.

With the ignition switch 197 and starter switch S closed, 1e operationof the throttle pedal T to partially open le throttle will energize theelectromagnet 173 by clos- .g the circuit between contacts 183 and 184with slider i1, and contacts 185 and 186 with slider 182. The final tngeof movement of the throttle pedal causes the sliders i1 and 182 to closethe circuit from contact 183 to conct 190, and from contact 186 tocon-tact 191, thereby versing the flow of current through the :t 173.

AIR INDUCTION SYSTEM FOR THE ENGINE The engine (not shown) is providedwith an air in- 182 of the switch 28. This switch 30 servo-motor. Theunderside of the leading edge of the air valve 37 has a deflector orspoiler 37a fixed thereto. Below the air valve 37 is a throttle valvemounted on a throttle shaft 51 and operated by lever 152 through a 5throttle linkage R from the accelerator pedal T. A slotted partition 49extends between the throttle shaft 51 and the air valve shaft 36.

The body of the air horn B has a bypass passage 80 controlled by ametering screw 278, which extends around the edge of the air valve 37when in the closed position. By adjustment of this screw 278, it ispossible to vary the position of the air valve 37 in the low range ofengine speeds at idle and slightly above. Since the air valve, in turn,controls the size of the fuel metering orifices 23, it is obvious thatthis adjustment 278 provides a fuel mixture control in the low range ofengine speeds by setting the position of the air valve and needles 33 inthe metering restrictions 23.

The air horn body B also has a by-pass 279 extending also 40 around theedge of the throttle 50 controlled by a metering screw 277. This by-passis operative when the throttle is closed to adjust the amount of airflowing to the engine, and, in this sense, controls the engine idlingspeed.

FUEL MIXTURE CONTROL REGULATION FOR ACCELERATION In order to obtainsolid throttle response in most. engines, it is necessary to increasethe fuel-air ratio fed to the engine simultaneously with throttleopening; in other words, the pressure carburetor or injection systeme1ectmmag 50 should perform a function of changing the fuel-air ratiosimultaneously with throttle opening to accomplish the result performedin the carburetor by the accelerating pump.

One way of accomplishing this particular result conti System h i an ihorn B communicating with 55 templates the use of a means responsive tothrottle openplurality of branches 26a which lead to the mbustionchambers of the engine. These separate anches 26a are, in turn,controlled by separate intake .lves 26. Since the parts of the airinduction system separate ing for elfecting a sudden movement of the airvalve in an opening direction, which, in turn, withdraws the meteringrods 33 from the orifices 23, increasing the fuel flow to the nozzles25. This means, actually, causes air ot shown) are conventional, nodescription or 111 valve 37 to over-travel in response to throttleopening by ttion is here included.

AIR MEASURING DEVICE Within the air horn B is an air valve 37 fixed on aatable shaft 36. The shaft is extended by dotted lines either side ofthe air horn, and one end thereof carries a half of magnetic clutch 35.The movements of the valve 37 rotate the shaft 36 which, in turn,positions fuel metering needles 33 through the interconnection themagnetic clutch 35. The opposite end of the shaft connects with atemperature responsive means 102 ich has a free end 103 positioned tomove into abutting ttion with one end of a lever fixed to the opite endof the shaft 36. The inner end of the thermo- 102 is carried in the slotin the hub of lever 101 75 applying forces thereto which actindependently of, or augment, those forces regulating air valve positionin response to the rate of air flow past the valve or the pressure dropacross the valve.

One structure for accomplishing this result is shown in FIG. 1, whereinthe air horn B is provided withan extension on the servo-motor casingdivided into two chambers and 126 by a diaphragm 127. A spring 128 urgesthe diaphragm 127 in a direction to compress the air in chamber 125.Chamber 126 is connected by a line to the air horn B posterior of thethrottle 50, and is thereby subjected to manifold pressure. Chamber 125is connected by a by-pass passage 129 to the chamber 41 of theservo-motor. The inlet opening to the chamber 41 from the vent tube 44is controlled by a leaf spring type of valve 200 ordinarily biased tothe open position.

OPERATION OF MIXTURE CONTROL RESPONSIVE TO THROTTLE MOVEMENT Duringoperation of the engine with the throttle 50 within the range fromclosed to part throttle positions, sufficient suction is presentposterior thereof acting in the chamber 126 to hold the diaphragm 127 inthe position illustrated, with the spring 128 compressed. If thethrottle is suddenly opened from any position within this range, suctionin chamber 126 becomes iusufiicient to maintain spring 128 compressed sothat spring 128 expands, forcing the air within the chamber 125 into thechamber 41. The increase in pressure in chamber 41 closes leaf springvalve 200 and, at the same time, causes the diaphragm 40 to be flexedagainst the compression spring 43, thereby forcing the air valve 37 torotate in the opening direction beyond the normal position which itwould take in response to the increasing rate of air flow through theintake stack B. This over-travel is a temporary matter, since there isalways some leakage past the valve 200, and the excessive pressurewithin the chamber 41 will eventually dissipate. It will be appreciated,however, that during the time in which the temporary high pressureprevails in the chamber 41, valve 37 will over-travel in the openingdirection, causing the needles 33 to withdraw from the metering orifices23 to temporarily increase the fuel flow to the nozzles 25.

PART THROTTLE AND FULL THROTTLE MIXTURE CONTROL Most engines of theautomotive type will operate satisfactorily on a leaner mixture in thepart throttle range corresponding to road load operation than in thesubstantially full throttle range corresponding to the full loadoperation. For this reason, it is possible to go to the carburetor artfor an analogy. For example, it is customary practice in carburetors touse stepping metering rods in the fuel metering orifices which areoperated in response to changes in manifold pressure. The size of thefuel metering orifice is increased by proper rod movement, to enrich thefuel mixture throughout the range of engine speeds within the full openrange of throttle positions.

The mechanism just described is usually referred to as a step-up in acarburetor. The corresponding function is performed in my priorapplication by a control in the datum pressure line. In the instantinvention, the same function is performed by a means responsive to acondition indicating increases in load on the engine, which will act toincrease the fuel flow to the engine. This means in the presentinvention accomplishes this func tion by changing the responseindications of the air valve 37 to the rate of air flow through the airhorn B. This mechanism is mounted on the air horn, or adjacent the airhorn, and connected with the servo-motor in the following manner.

In the wall of the air horn anterior of the air valve 37 are a pair ofports 202 and 203 so placed that they are within a zone influenced bythe passage of air between the wall of the air horn B and the edge ofthe air valve 37 when the latter is in a partially open position. Theseports connect with a common passage communicating by way of a tube 205with a chamber 206 in the casing 207. A diaphragm 208 separates chamber206 from chamber 210. The diaphragm 208 is biased in one direction by aspring 211, and carries a valve 212 which operates to and from a valveseat in a metered restriction at the entrance of tube 213, which, inturn, connects with the chamber 42 of the servo-motor by way of the lineextending from the Pitot tube 45. Chamber 210 is connected with the airhorn B posterior of the throttle 50 by a tube 209. Suction posterior ofthe throttle is thereby communicated to the chamber210 to compress thespring 211 and separate the valve 212 from its seat.

6 If there is insuflicient suction in chamber 210, the spring 211 willclose the valve 212.

OPERATION OF PART THROTTLE AND FULL THROTTLE MIXTURE RATIO CONTROL Inthe part throttle range of engine operation, it can be assumed thatengine intake manifold depression is always greater than six inches ofmercury. Accordingly, spring 211 is calibrated in such a manner as toretain the valve 212 unseated, so that restricted amount of air bleedsfrom the ports 202 and 203 (when one or both are anterior of the airvalve 30) through the chamber 206 and line 213 to modulate the suctionin chamber 42 sensed by the Pitot tube 45. The power exerted by theservo-motor on the air valve 37 and against the spring 43 is therebyreduced an amount which will cause a substantial pressure drop in theair horn B across the valve 37. In other words, the opening movement ofthe air valve 37 is somewhat restricted by the operation of the bleedfrom the ports 202 and 203, and the position which the air valve 37assumes, results in a displacement of the needles 33 in the orifices 23only sufiicient to give a mixture proper for part throttle, road loadoperation of the engine.

After the air valve 37 reaches a substantial open position within therange of 55 or 60, however, ports 202 and 203 are posterior of the valveand within the high velocity air stream which will be passing betweenthe side wall of the air tube B and the deflector 37a on the air valve37. This drop in pressure, due in part to the high velocity stream, caneither cut off or substantially reduce the flow of air through the ports202 and 203, and come quently the amount of air bled past the valve 212and through line 213 to chamber 42. When the air bleed through ports 202and 203 is stopped, the servo-motor exerts a greater force on the airvalve 37 directly proportional to the drop in pressure measured by thePitot tubes 44 and 45, thereby opening the air valve 37 to decrease thedrop in pressure across the valve 37 The response of the air valvecauses the needles 33 to move out of orifices 23 sufiiciently to providethe power range of fuel mixtures necessary. Generally, this occurs inthe higher ranges of engine speed and throttle openings.

At any engine speed, throttle opening which decreases manifold suctionto less than the arbitrarily selected example of six inches of mercurycauses spring 211 to expand, closing valve 212 and cutting off the bleedfrom the ports 202 and 203 so that the air valve assumes a positionunder control of the drop in pressure measured between the Pitot tubes44 and 45 exclusively. The pressure drop across the valve 37 therebybecomes minimum, and the angular displacement of the valve is increasedto withdraw the needles 33 and give increased fuel delivery(corresponding to a full power mixture). Conversely, the reverseoperation occurs if the throttle is closed at any engine speed.

From the above described operation, it will be readily understood thatthe air valve 37 may take up two distinctly difierent positions for thesame rate of air flow. The smaller amount of displacement will occur inthe part throttle range of operation of the engine so long as manifoldsuction indicates low engine loads. Larger displacements of the valve 37will occur as soon as the valve opening exceeds 55 or 60, or if thethrottle is opened wide enough to decrease the manifold suction belowsome arbitrary point such as, for example, the intake manifolddepression of six inches mercury pressure mentioned.

It is contemplated that the contour of the needles 33 is such that thedisplacements produced by the air valve 37 when the engine is operatedthroughout its speed range at full throttle will give the proper fuelfiow through the orifices 23 to match the fuel-air ratios demanded bythe engine at full load. This means that the part throttle mixtureratios delivered by lesser displacements of the air valve 37 for thesame rate or air flow produce lesser dis placements of the needles 33 inthe orifices 23. The de- 7 me of change in needle displacement can besuitably conrolled by calibration of the ports 202 and 203, by variaionsin port location and size. Obviously, these ports can e placed in such arelation to the air valve 37 as to be Iithin the influence of the airstream passing between 1e wall of the air horn and deflector 37a at anypoint in ie opening movement of the air valve. Thus the ports an beprogressively subject to a zone of low pressure adtcent the deflector37a, which zone will progressively ass over the ports as the air valve37 opens. Accordingthe pressure at the ports 202 and 203 is a variablespending upon air valve displacement.

The shape of the part throttle fuel mixture curve can e determinedarbitrarily by a change in location and ze of the ports, and thiscalibration is flexible over a lbstantial portion of the range ofopening movement of re air valve 37.

OPERATION OF FUEL INJECTOR To start the engine, it is first necessary toclose the nition switch 197 and then crank the engine by closing l6starter switch S, which, incidentally, energizes the )ntacts of switch28. When the engine is below normal aerating temperature, thermostat 102will wind up exertg a force on the lever 100, so that when the throttleis trtly open, as is proper during a cold start, the air valve 7 canopen in response to thermostat action and increase .e amount of fueldelivered to the engine. After the lgine starts, manifold suction actingon the piston 105 ill decrease the opening movement produced on the airtlve 37 by the thermostat 102 so as to reduce the fuel ixture ratio tothat proper for warm-up. The force Lerted by the thermostat 102decreases as the engine mperature increases until, at normal enginetemperares, the end 103 moves out of contact with the lever t0, leavingthe air valve free to be controlled by the rvo-motor. The action of thethermostat 102 on the air LIVE 37 affects the displacement of the airvalve 37 with spect to air flowing through the air horn B and in arection to withdraw the needles 33 from the orifices 23 ld increase thefuel mixture ratio during cranking and arm-up. The throttle pedal T alsocan be opened far enough, if eded, to prime the engine with excess fuelregardless of e action of the engine temperature controlled enrichentproduced by the above-described mechanism. The iming operation isaccomplished during cranking by iening the throttle part way to closethe switch 2S. In is throttle position or range, contacts 183 and 184are used by the slider 181, and the contacts 185 and 186 are )sed by theslider 182. This energizes the electromagnet 3 in the pressure regulator60, applying a force to the rmanent magnet 172 to compress the spring180 and aver the pressure tending to close the valve 167. When the forceof spring 180 is reduced by the action the electromagnet, the regulatedpressure maintained the pressure regulator 60 is reduced, and thepressure ferential across the metering restriction 61 increases bycorresponding amount. During normal operating conditions of the system,the assure in the datum system is controlled by the regula- C, and thepresence of the metering orifice 58H has effect upon the function of theregulator C because of very small amount of flow permitted by thecoaction the orifice 61 and the regulator 60. The orifice 61 is smallerof the two flow restrictions SSH and 61. As will be apparent, the basicdatum system has two w metering restrictions, SSH and 61, in series,operating a controlled pressure drop between regulator C and gulator 60.With two or more fixed restrictions in ies, a certain amount of meteringwill be done by all so 1g as there is a measurable pressure drop acrosseach :triction. Also, there is less metering done at the largertriction. Consequently, metering requires a pressure In this system,restriction 58H is larger than restriction 61, and at normal flow thereis no measurable pressure drop across the restriction 58H. If the flowthrough the datum system is increased, the pressure drop across 58Hbecomes significant. In other words, the more the flow, the greater thepressure drop and the greater the metering effect of restriction 58H.

When rates of flow through the orifice 61 increase above normal, therewill be a substantial increase in the pressure drop across the orifice58H, lowering the pressure in the datum system to increase the flowthrough the nozzles 25 by increasing the pressure drop across themetering orifices 23 which provide the metering in the engine chargingsystem. During the priming operation, however, the function of thepressure regulator C to establish a fixed datum pressure is modified bythe action of the orifice 58H. The metering effect of this orificeprevents the regulator C from maintaining the pressure when the flow inthe system is increased by lowering the pressure downstream or orifice61 to reduce the back pressure maintained by regulator 60 as abovedescribed.

When the engine starts, the starter switch is opened, therebyde-energizing the circuit to the electromagnet 173 in the pressureregulator 60. This builds up the pressure downstream of the meteringrestriction 61, decreasing the rate of flow to the normal, which isabout 3 /2 pounds an hour. At this low rate of flow, there is nomeasurable pressure drop across the metering restriction SSH, and thepressure in the datum system will increase to the setting of thepressure regulator C. Flow through each of the nozzles 25 will decreaseas the datum pressure increases, raising the pressure downstream of themetering orifices 23. Thus, under normal operation of the system, thepressure drop across the metering orifices 23 becomes the same as thepressure setting of the regulator C, and is maintained constant by thisregulator.

If, during the starting of the engine, the combustion chambers areflooded so that unloading is necessary, then the throttle T is fullyopened so that the switch 28 closes the circuit between contacts 183 andand 186 and 191 to reverse the flow of current through the electromagnet173, changing its polarity. This effects a new relation between theelectromagnet 173 and the permanent magnet 172, placing like polesopposite, and produces an added force augmenting the force of the spring180, both forces acting in the direction to close the valve 167. Thepressure downstream of the metering restriction 61 will be increased,and this effect will be. felt throughout the datum system, since whenflow stops in the datum line 58, the pressure will increase, tending toclose the valve 75 in the regulator C and open the valve 76-. However,the closing of valve 167 will prevent discharge through the line 79,tending to lower the datum pressure, so that the datum system becomesmore or less a sealed system at a higher pressure than normal toeffectively close the nozzle valves 25 and shut off the flow of fuel tothe engine.

During cranking and running of the engine, pump P will be operating,delivering fuel through the pressure regulator 22 into the fuel chamberA. The metering of the fuel is accomplished by varying the area of themetering orifices 23 in the fuel chamber A, and these variations in areaare accomplished simultaneously and equally by a plurality of meteringrods 33-controlled fromthe position of the air valve 37 through themagnetic clutch 35. As above explained, the air valve 37 will assumepositions indicating the rate of air flow to the engine for both thepart throttle and full throttle range of engine operation, dependingupon engine load.

In this system, the pressure drop across each of the orifices 23 ismaintained equal by regulating nozzle valves 25 which are primarilycontrolled by the pressure regulator C, which is supplied with fuel atchamber pressure A through the line 56. The action of the pressureregulator C is such that a constant pressure difference is maintainedbetween the pressure in line 56 and in the datum system line 58,regardless of engine operating conditions or pump pressure fluctuations.Only during cranking is the datum pressure variable. The construction ofthe pressure regulator C is such that the charging pressure in line 56tends to open the valve 75 of the regulator, while back pressure fromthe datum system through the line 58a and connection 59 tends to closethe valve 75. The difference between the charging pressure and the datumpressure is actually controlled by the spring 74 biased against theeffective area of diaphragm 71.

As described above, the effect of sudden throttle opening on the systemincreases the flow of fuel through each of the lines 24 by withdrawingthe needles 33 and increasing the size of the metering orifices. Thisaction is due in part to the over-travel produced on the air valve 37 bythe pumping action of the diaphragm 127 and in part to increase airflow. The increase in the rate of fuel flow through the lines 24 causesan increase in fuel pressure in chambers 30, which moves the diaphragms28 in each of the nozzles in a direction to displace fuel from chambers57 on the opposite sides of the diaphragms into the datum pressuresystem, and primarily into line 58, Unless provision is made in thesystem to accommodate the fuel displaced by each of the diaphragms 28,there will be an instantaneous pressure rise in the datum system whichwill resist instant opening of nozzle valve 29, and throttle response ofthe engine will be adversely affected by the lag in the nozzle valveaction.

It is a feature of this invention to compensate for this condition bythe valve 76 connecting with the pressure relief by-pass line 79, forconducting any excess fuel from the datum system to a point downstreamof the centrifugal metering jet 61.

Thus, any instantaneous pressure increase in the datum line 58 iscompensated for by the fact that diaphragm 71 will respond, openingrelief valve 76 to discharge fluid from line 58 and thus prevent thebuild-up of back pressure caused by the displacement of the diaph-ragms28.

From this description of the operation it will be readily understoodthat there is a definite cooperation between the action of the pressureregulator C and the mechanism in the air horn structure controlling thedisplacement of the air valve 37, although these devices are controlslocated in separate systems incorporated in the device.

FIRST MODIFIED FORM In the form of the invention hereto-fore described,the pressure regulator C in the datum pressure system is locatedupstream from each of the nozzles 25, but this location is not criticalto the proper functioning of the system. Actually, the pressureregulator C may just as well be located downstream of the nozzles 25 inthe datum pressure system, and yet, in this location, perform in thesame manner to produce a similar result.

FIG. 2 illustrates a variation of the combination of elements shown inFIG. 1 in which the pressure regulator C is actually located downstreamof the injection nozzles in the datum pressure system.

In FIG. 2 the same reference characters have been used to indicate likeparts corresponding with those shown and described in FIG. 1. Thedetailed description which follows will emphasize the differencesbetween the systems of FIG. 1 and FIG. 2, which differences are confinedto the datum pressure system. It is believed that the precedingdescription will serve to explain the construction and operation ofother parts of the system illustrated in FIG. 2.

According to FIG. 2, the datum pressure system is connected to thepressure chamber A by a line 58, and communicates therewith by way of asuitable metering restriction 55. As will be pointed out hereinafter,restriction 55 permits a continuous circulation from the chamber Athrough the datum pressure line to eliminate the accumulation of air orvapors therein, or to remove any 10 air or vapors trapped therein incase the fuel supply fails. If the fuel tank of the vehicle goes dry,some provision must be made to bleed the system of air.

The datum pressure line 58 has branches 58a, 58b, 58c and 58d, each ofwhich connects with the datum pressure chambers of the nozzles 25.Adjacent the outlet of the line 58 is the pressure regulator C, which isof the same construction as that heretofore described. The pressure inthe line 58 is imposed against a diaphragm 71 of the pressure regulatorC. The opposite side of the diaphragm communicates with the pressuredownstream of the regulator 22 by way of the line 56, which has the samepressure as 20a and chamber A. Branch 59 connects the line 58 with thechamber of the pressure regu lator C downstream of valve 75 and extendsfrom this chamber to the metering orifice 61. A line 79 connects theoutlet of the pressure regulator relief valve 76 with a restrictedpassage 163 leading to the outlet valve 167 of the pressure regulator60, The construction of the pressure regulator C is identical with thatabove described.

OPERATION OF MODIFIED FORM In this modification, it is preferred to makethe metering orifice 55 smaller than the metering orifice 61, and ofless capacity. When this relationship exists, the datum pressure isactually under control of the regulator C, which opens the valve 75slightly, under normal conditions, to raise the datum pressure in theline 58 to the desired differential between the chamber and line 58. Thediaphragm 71 is balanced by the force of charging pressure from the line56 on one side, and datum pressure plus the force of the spring 74 onthe opposite side, so that the difference between charging pressure anddatum pressure is determined by the force of the spring 74. Under steadyconditions, the diaphragm 71 will take up a position opening the valve75 slightly so that fuel will be flowing into the datum system throughboth the orifice 55 and the valve 75.

If the datum pressure in line 58 should increase for any reason, such asthe rapid withdrawal of the needles 33, which would cause the opening ofthe valves 25 and displacement of the diaphragms 28 therein, thepressure regulator C will react, closing the valve 75 and opening thevalve 76 to bleed the pressure rapidly from the datum pressure line 58through the line 79 into the chamber 164 of the pressure regulator 60.As before explained, the effect produced on the pressure regulator 60opens the valve 167 thereof, dropping the pressure downstream of themetering restriction 61. This effect produces a lowering of the datumpressure throughout the entire datum pressure system by increasing thedischarge through the metering restriction 61 so that fuel can escape.At this point it should be noted that the restriction 163 in the passage163 will cause a delay in the pressure drop in chamber 164, and thisdelay maybe regulated by proper calibration of this restriction. Byvariations in restriction size, the downstream pressure drop can havemore or less an instantaneous effect upon the system, or a prolongedeffect.

As has been explained heretofore, when the pressure drop across orifice61 increases, the flow therethrough increases, which makes therestriction 56 more effective as a pressure control. A greater dropacross 61 causes a greater drop across orifice 58' and lowers the datumpressure, increasing the flow from each of the nozzles 25. This increasein flow increases the mixture ratio temporarily for acceleration of theengine, If the particular engine requires a prolonged enrichment forsatisfactory performance, then the restriction 163' placed in thepassage 163 may be suitably selected to attain this purpose.

For other engines having different characteristics, it may be desirableto have the enrichment of the mixture take place over an extremely shortperiod of time. In such a case, it may not be desirable to prolong thepressure drop in the datum system by increasing the discharge I ltherefrom through the metering restriction 61, as heretofore described.For such an engine, a dilfe-rent system is proposed which includes adifferent interconnection between the same parts of the system as abovedescribed. Such a system is shown in FIG. 3.

SECOND MODIFIED FORM In the system illustrated in FIG. 3, the samereference characters have been used, where possible, to indicate likeparts, and the description thereof will be limited to the differences inthe interconnections between the parts.

According to FIG. 3, the pressure regulator C is connected by a line 79directly with the inlet of the pump P, line 19. In the line 79 is asolenoid valve SV powered by a circuit 139 energized on closing of theignition switch 197. The valve is retained open when the engine ignitionswitch is on, and a spring 245 closes the valve when the ignition isturned off.

OPERATION OF FIG. 3

In this system, the operation of the pressure regulator C produces nodelaying eifect upon the pressure regulator C produces no'delayingeffect upon the pressure regulator 60. Consequently, the action of thetwo regulators C and 60 is distinct. The regulator C will retain thepressure in the line 58 in the same manner as above described, andfurther respond to any increase in pressure in the datum pressure line58 to relieve this pressure through the valve 76 so long as the engineis operating. The opening of the valve 76, however, will produce verylittle fluctuation in the datum pressure line 58. In this system, itsfunction is primarily to prevent the pressure therein from exceeding thefixed or regulated pressure established by the diaphragm 71. What slightlowering of the pressure does occur below the regulated pressure will bevery short in duration. In this respect its action differs from theprior described devices.

When the engine is shut off by turning off the ignition switch 197,solenoid valve SV will close so as to prevent any bleed-down in thedatum pressure line 58.

MODIFIED FORM OF FUEL MIXTURE CONTROL REGULATION FOR ACCELERATION In thedescription of FIG. 1 a means was described to obtain solid throttleresponse of the engine. This means was likened in result to the eifectof an accelerating pump in a carburetor. In FIG. 4 is shown a modifiedform of such a device which is mechanically actuated from the throttle,instead of pneumatically actuated from manifold pressure.

In FIG. 4 the same reference characters have been used to indicate likeparts, and this description will be limited to the modified form of thedevice operating to attain this result. The throtle operating shaft 51carries a fixed lever 235 connected with a rod 234 which extends withina tube 233, which guides the rod 234' during movement of the throttlefrom open to closed positions. The tube 233 is attached to a diaphragm231 in a suction pump casing 230. The rod 234 is not solidly attached tothe diaphragm, and actually forms a one-way operating connection forforcing the diaphragm 231 against the pressure of a spring 232 when thethrottle is moved in the closing direction. Opening movement of thethrottle Withdraws the rod 234 within the tube 233, permitting thespring 232 to expand, moving the diaphragm 231 to the left.

The movement of the diaphragm 231 to the left produces a depressionwithin the diaphragm chamber of the pump 230, which is communicated byWay of the line 236 controlled by restriction 237 to the suction chamber42 of the servo-motor for operating the air valve 37. A second line 238connects the pump chamber to the servomotor chamber 42, and iscontrolled by a check valve 239, which closes in response to the actionof the pump 230 when the throttle is opened, and opens when the throttleis returned.

The connection between the Pitot tube 45 and lead line 213 with theservo-motor chamber 42 is controlled by a oneway check valve 240 whichopens when the pressure in the lines 213 and 45-is less than in thediaphragm chamber 42 of the servo-motor. The check valve 240 is hereillustrated as a ball valve and is designed to have a slight leakagewhen closed, due to the fact that the depression in the chamber 4-2 isless than in the connecting lines 213 and Pitot tube but it iscontemplated that a flat check valve may be used at this point actuatedin the same manner by the same differential pressures and provided witha metered hole, if desired. The size of that hole will control theduration of over-travel of the air valve 37, as will be explainedhereinafter.

OPERATION In this modification, opening movement of the throttle 553 byoperation of the throttle control arm I52 connected with the throttlepedal T permits expansion ofthe spring 232 and movement of the diaphragm231 to the left, as viewed in FIG. 4. Since the check valve 239 isclosed, diaphragm movem nt creates a depression within the suction pump23% which is communicated by Way of the line 236 to the chamber 42 ofthe servo-motor controlling the air valve 37. The strength of the spring232 is suificient to produce an action of the diaphragm 231 which israpid, and which will close the check valve 249 so that the pumpingaction will be communicated directly to the chamber 42 to affect airvalve position by increasing the differential pressure across thediaphragm 40 of the servo-motor. As the valve 37 opens in response tothe action of the pump 235), metering needles 33 Will be Withdrawn toincrease the flow of fuel to the nozzles 25 and thereby increase themixture ratio by supplying a greater amount of fuel to the engine. thiselfect, as well as the rate of response of the air valve 37, can beeasily controlled by adjusting the leakage past the check valve 246 andthe size of the restriction 237. As above mentioned, if a disk valve isused, it can be formed with a hole for metering the leakage past thevalve 24%.

When the throttle 5% is closed by removing pressure from the throttlepedal T, a return spring in the linkage moves the throttle toward closedposition until the rod 234 begins to force the diaphragm 231 to theright, forcing the air trapped in the diaphragm chamber of the pump 230out of the chamber through the lines 236 and 238. Since both lines 233and 2.37 can open, the rate of closing movement of the throttle is notsubstantially retarded, and the effect on the servo-motor is rapid. Inall other respects, the modification in FIG. 4 is constructed andoperates in the manner already described above with reference to FIG. 1.

The foregoing describes a structure which will perform all of thefunctions and attain all of the resuits set forth above, but it iscontemplated that other modifications will occur to those skilled in theart which come within the terms of the appended claims.

I claim:

1; An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a valve insaid air stream, a servo-motor for moving said valve in an opening diection, and a source of power for operating said servomotor in responseto changes in the rate of flow in the air stream past said valve so thatchanges in air valve position produced by said servo-motor indicate ameasure of the rate or" air flow to the engine, a throttle valve in theair stream for limiting the flow of air to the engine, and meansresponsive to throttle movement connected to said servo-motor fortemporarily changing the power output of said servo-motor and therebythe rate of The duration of 13 response of said air valve to changes inthe rate of air flow past said valve.

2. An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising means formeasuring the flow of air to the engine, said means including a membermovable in the air stream in response to variation in the rate of airflow to the engine, means for measuring the flow of fuel to the engine,a connection between said measuring means to maintain the flow througheach stream proportional to the other, a throttle valve in the airstream for limiting the rate of air flow, and means connecting saidmovable member with said throttle and operated by said throttle fortemporarily and suddenly changing the proportions of fuel flow to airflow during throttle movement.

3. An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a valve insaid air stream, a servo-motor for moving said valve in an openingdirection, a source of power for operating said servo-motor in responseto changes in the rate of flow in the air stream so that changes in airvalve position indicate a measure of the rate of air flow, means formeasuring the flow of fuel to the engine, a connection between saidmeasuring means to maintain the flow through each stream proportional tothe other, a throttle valve in the air stream for limiting the flow ofair to the engine, and means connecting said fuel metering means andsaid throttle for temporarily and suddenly changing the proportions offuel flow to air flow during throttle movement.

4. An engine charge forming deviw having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a valve insaid air stream, a servo-motor for moving said valve in an openingdirection, and a source of power for operating said servo-motor inresponse to changes in the rate of flow in the air stream so thatchanges in air valve position indicate a measure of the rate of airflow, means for measuring the flow of fuel to the engine, a connectionbetween said measuring means to maintain the flow through each streamproportional to the other, a throttle valve in the air stream forlimiting the fiow of air to the engine, and means responsive to throttlemovement for temporarily changing the proportions of fuel flow to airflow by modifying the source of power supplied to said servo-motor.

5. An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a valve inthe air stream, a servo-motor for operating said valve in an openingdirection, means for operating said servo-motor in response to changesin pressure differential in the air stream across said valve, wherebythe position of the valve in the air stream becomes a measure of airflow to the engine, means for measuring the flow of fuel to the engine,a connection between said measuring means to maintain the flow througheach stream proportional to the other, a throttle in the air stream forlimiting the air flow to the engine, means connected to said servo-motorcomprising an air bleed passage, and inlet ports for said passagelocated in the air stream adjacent the opening edge of one of saidvalves.

6. An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a valve inthe air stream, a servo-motor for operating said valve in an openingdirection, means for operating said servo-motor in response to changesin pressure differential in the air stream across said valve, wherebythe position of the valve in the air stream becomes a measure of airflow to the engine, means for measuring the flow of fuel to the engine,a connection between said measuring means to maintain the flow througheach stream proportional to the other, a throttle valve in the airstream for limiting the air flow to the engine, and means connected tosaid servomotor and operated by changes in pressure downstream of thethrottle including a suction operated valve to modify the action of saidservo-motor, an air bleed passage controlled by said valve and connectedto said servomotor, and inlet ports for said passage located in the airstream adjacent the opening edge of said air valve.

7. An engine charge forming device having a system for maintaining theflow of fuel to the engine in one stream proportional to the flow of airto the engine in a separate stream, said device comprising a throttlecontrolling the flow of air to the engine, a variable capacity airmetering means for measuring the air flow past said throttle, means forvarying the capacity of said air metering means to maintain the rate ofair flow therethrough Within a given range in the higher range of enginespeeds and throttle openings, means to modify the response of said airvalve to the rate of air flow at different engine speeds and lower rangeof throttle openings, a second variable capacity metering means in saidfuel stream operated directly by changes in capacity of said variablecapacity air metering means whereby the capacity of both metering meansis increased or decreased together, and throttle operated means fortemporarily varying the response of said air metering means.

8. In an engine charge forming device having an air conduit with an airinlet and air outlets connected with the combustion chambers of theengine, a throttle valve in said inlet, a fuel chamber receiving fuelunder pressure and delivering fuel under pressure to the combustionchambers of the engine through separate branches, and a system formaintaining the flow of fuel proportional to the flow of air, saidsystem comprising: a disk valve in said inlet, a pivot about which saidvalve is hinged for swinging movement to form a variable air flowrestriction in said inlet, a deflector surface on the leading edge ofsaid valve relative to the direction of air flow to said engine, saiddeflector surface being positioned on said valve to coact with the airstream and the wall of said inlet so as to modify the slope of the curverepresenting opening torque for the valve, a motor connected to operatesaid valve to vary the opening area of said air flow restriction, ameans sensitive to velocity of the air stream passing the valve forcontrolling the power output of said motor to determine the position ofsaid valve in the air stream in response to changes in velocity sensed,means responsive to throttle opening for effecting a sudden movement ofthe air valve in an opening direction, and fuel metering means in saidbranches operated by change in position of said valve.

9. In an engine charge forming device having an air conduit with an airinlet and air outlets connected with the combustion chambers of theengine, a throttle in said inlet, a fuel chamber receiving fuel underpressure and delivering fuel under pressure to the combustion chambersof the engine through separate branches, and a system for maintainingthe flow of fuel proportional to the flow of air, said systemcomprising: a disk valve in said inlet anterior of said throttle, apivot about which said valve is hinged for swinging movement to form avariable air flow restriction in said inlet, a deflector surface on theleading edge of said valve relative to the direction of air flow to saidengine, said deflector surface being positioned on said valve to coactwith said air stream and the Wall of said inlet so as to modify theslope of the curve representing opening torque for the valve, a motorconnected to operate said valve to vary the open area of said air flowrestriction, a means sensitive to the pressures in the air streampassing the valve and operative in response to 15 throttle movement forcontrolling the source of power for operating the servo-motor todetermine the position of said valve in the air stream in response tochanges in pressures sensed, means connected with said motor andoperated by changes in load on said engine for modifying the action ofsaid motor, and fuel metering means in said branches operated by changesin position of said valve.

10. In an engine fuel charging system of the pressure type having a fuelinlet, a fuel outlet for discharging fuel to the engine, a pumpsupplying fuel under pressure to said inlet, a fuel line normallypressurized from said pump connecting said inlet and said outlet, apressure regulator having a movable wall controlling a valve at saidoutlet, a datum pressure system including a by-pass extending aroundsaid pump, and opposed expansible chambers sep. arated by said movablewall and connected with said datum system and said fuel line,respectively, whereby said regulator maintains the fuel in said fuelline at a pressure proportional to the controlled pressure in said datumsystem, the combination therewith of means for establishing a controlledpressure in said dataum system at a fixed differential with respect tosaid pump supply pressure, a datum pressure relief passage from saidcontrol means, and means responsive to a pressure increase in saidestablished' datum pressure from said fixed differential for openingsaid pressure relief passage.

11. In an engine fuel charging system of the pressure type having a fuelinlet, a fuel outlet for discharging fuel to the engine, a pumpsupplying fuel under pressure to said inlet, a fuel line normallypressurized from said pump connecting said inlet and said outlet, apressure regulator having a movable wall controlling a valve at saidoutlet, a datum pressure system including a by-pass extending aroundsaid pump, and opposed expansible chambers separated by said movablewall and connected with said datum system and said fuel line,respectively, whereby said regulator maintains the fuel in said fuelline at a pressure proportional to the pressure in said datum system,the combination therewith of means for establishing a controlledpressure in said datum system proportional to the fuel supply pressurecomprising a metering restriction in said by-pass downstream of saidpressure regulator, means controlling the pressure drop across saidmetering restriction, a datum pressure relief passage by-passing saidrestriction, and means responsive to a pressure increase in said datumpressure system from said established proportional pressure for openingsaid pressure relief passage.

12. In a fuel charging system of the pressure type having a fuel inlet,a fuel outlet for discharging fuel to the engine, a pump supplying fuelunder pressure to said inlet, a fuel line normally pressurized from saidpump connecting said inlet and said outlet, a pressure regulator havinga movable wall controlling a valve at said outlet, a datum pressuresystem including a by-pass extending around said pump, and opposedexpansible chambers separated by said movable wall and connected withsaid datum system and said fuel line, respectively, whereby saidregulator maintains the fuel in said fuel line at a pressureproportional to the pressure in said datum system, the combinationtherewith of means for establishing a controlled pressure in said datumsystem at a relative differential with respect to said fuel supplypressure, said means comprising a metering restriction in said by-passpassage, means for regulating the pressure upstream and downstream ofsaid metering restriction, a pressure relief by-pass extending aroundsaid metering restriction to the inlet of said pump, means responsive toa pressure rise in said datum system from said established differentialpressure for closing the supply of fuel to said datum system and foropening said relief by-pass passage, and means in said datum system forlimiting the rate of pressure rise therein.

13. In an engine fuel charging system of the pressure type having a fuelinlet, a fuel outlet for discharging fuel to the engine, a pumpsupplying fuel under pressure to said inlet, a fuel line normallypressurized from said pump connecting said inlet and said outlet, apressure regulator having a movable wall controlling a valve at saidoutlet, a datum pressure system including a bypass extending around saidpump, and opposed expansible chambers separated by said movable Wall andconnected with said datum system and said fuel line, respectively,whereby said regulator maintains the fuel in said fuel line at apressure proportional to the pressure in said datum system, thecombination therewith of means in said datum system to accommodate fueldisplaced by movement of said movable well during valve opening toincrease the fuel supply to the engine, said means comprising a secondpressure regulator in said datum system supplied with fuel from saidpump and controlling the pressure in said datum system, a datum pressurerelief line connecting said second pressure regulator with the intake ofsaid pump, and valve means in said second pressure regulator for closingthe supply thereto and opening the relief passage thereof in response toincreases in pressure in the datum system beyond the pressure setting ofsaid second pressure regulater.

14. In an engine fuel charging system of the pressure type having a fuelinlet, a fuel outlet for discharging fuel to the engine, a pumpsupplying fuel under pressure to said inlet, a fuel line normallypressurized from said pump connecting said inlet and said outlet, apressure regulator having a movable wall controlling a valve at saidoutlet, a datum pressure system including a by-pass extending aroundsaid pump, and opposed expansible chambers separated by said movableWall and connected with said datum system and said fuel line,respectively, whereby said regulator maintains the fuel in said fuelline at a pressure proportional to the pressure in said datum system,the combination therewith of means for establishing a controled pressurein said datum system proportional to the fuel supply pressure comprisinga metering restriction in said by-pass passage, means for regulating thepressure upstream and downstream of said metering restriction, apressure reiief by-pass by-passing said metering restriction andextending between said means for regulating the pressure upstream anddownstream thereof, means responsive to a pressure rise in said datumsystem for closing the supply of fuel to said datum system and openingsaid relief by-pass passage, and a connection between said reliefby-pass passage and said downstream regulator operating to communicateupstream pressure thereto to cause a pressure drop downstream of saidmetering restriction and a decrease in the datum pressure.

15. In an engine fuel charging system of the pressure type having a fuelinlet, a fuel outlet for discharging fuel to the engine, a pumpsupplying fuel under pressure to said inlet, a fuel line normallypressurized from said pump connecting said inlet and said outlet, apressure regulator having a movable wall controlling a valve at saidoutlet, a datum pressure system including a by-pass extending aroundsaid pump, and opposed expansible chambers separated by said movablewall and connected with said datum system and said fuel line,respectively, whereby said regulator maintains the fuel in said fuelline at a pressure proportional to the pressure in said datum system,the combination therewith of means for establishing a controlledpressure in said datum system at a substantially fixed differentialpressure with respect to the fuel supply pressure, said means comprisinga metering restriction adjacent the outlet of said by-pass passage, asecond metering restriction of greater capacity adjacent the inlet ofsaid by-pass passage, means for regulating the pressure upstream anddownstream of said metering restrictions, a pressure relief by-passconnected between said datum pressure system upstream of said meteringrestrictions to the inlet of said pump, means responsive to a pressurerise in said datum system for closing the supply of fuel to said datumsystem and opening said relief by-pass passage, and a connection betweensaid relief by-pass passage and said downstream regulator opcrating tocommunicate upstream pressure thereto to cause an increase in pressuredrop at said downstream metering restriction and a decrease in datumpressure.

16. A charge forming device for an internal combustion engine comprisingan induction passage, a throttle valve rotatably mounted in saidinduction passage, an air valve rotatably mounted in said inductionpassage anteriorly of said throttle valve, a servo device operativelyconnected to and adapted to control the position of said air valve inaccordance with the pressure drop across the air valve, conduit meansfor supplying fuel to said induction passage, means operativelyconnected to said air valve for controlling fuel flow through saidconduit means, and engine temperature responsive means for varying the18 degree of opening of said air valve during engine idling conditions.

References Cited by the Examiner 7/39 Browne 261-66 8/48 Mock 123119KARL I. ALBRECHT, Primary Examiner.

RALPH H. BRAUNER, Examiner.

